1. Field of the Invention
This invention relates to windings of dynamoelectric machines and more particularly to means for shaping the end portions of electrical coil bars for dynamoelectric machines.
2. Description of the Prior Art
Stator windings for dynamoelectric machines such as motors and generators often include a plurality of phase coils which are formed by connecting a plurality of axially extending conductors or coil bars at their ends. Such connections are generally made in the end turn regions of the stator and are called series connections. Such series connections join circumferentially separated coil bars necessitating angular displacements in the end turn regions for each joined pair of coil bars. Due to considerations such as the circumferential separation between coil bars, space limitations in the end turn regions, and avoidance of interference with other structural elements in the machines' end turn regions, the stator coil bars are frequently bent radially outward, circumferentially about, and finally generally parallel with the axis of rotation of the particular machine's rotatable shaft. The series of conductors and connections therebetween often form a frustoconical surface in the end turn regions.
Prior coil forming practice includes the use of concave and convex forming blocks, frequently made of wood, which provided the foundation against which the conductors or coil bars were deformed so as to properly shape them through hammering, pushing, twisting, and bending. Such coil bar formation has traditionally been accomplished manually with considerable effort and has resulted in a lack of shape uniformity among coil bars since there was no way to accurately control the manual forces being applied. Such imprecise shape duplication of coil bars increases the difficulty in both winding and serially connecting the coil bars. Such increased difficulty can adversely affect the machine's cost and quality while the manual shaping can promote non-interchangeability of replacement parts and decreased reliability due to residual stresses imposed on the coil bars. A further disadvantage of such forming blocks includes the vast amount of storage space required to house the blocks between times of actual usage.
An apparatus for producing standardized coil bar shapes would be advantageous from both a cost standpoint and reliability considerations.